Zoom module using rotational actuator with anti-lock feature, even force distribution and shock damage prevention methods

ABSTRACT

An optical module includes a first optics group, a second optics group, and an image sensor, wherein the first optics group and second optics group are configured to provide an image having a focus and a magnification to the image sensor. In some embodiments of the present invention, a first optics assembly includes a first optics group coupled to a threaded portion of a first lead screw so that translation of the first lead screw results in translation of the first optics group along an axis of the first lead screw, a first actuator for rotating the first lead screw; and a first sensing target configured to permit detection of rotation of the first lead screw. In some embodiments of the present invention a second optics assembly includes a second optics group coupled to a threaded portion of a second lead screw so that translation of the second lead screw results in translation of the second optics group along an axis of the second lead screw, a second actuator for rotating the second lead screw, and second means for sensing configured to detect rotation of the second lead screw.

RELATED APPLICATIONS

This patent application claims priority under 35 U.S.C. 119(e) of theco-pending U.S. Provisional Pat. App. No. 60/836,616, filed Aug. 8,2006, entitled “Miniaturized zoom module with rotational piezo actuatorwith anti-lock feature, even force distribution, shock damage preventionand a novel position sensing methods”, which is hereby incorporated byreference.

In addition, this patent application is a continuation-in-part ofco-pending U.S. patent application Ser. No. 11/514,811, filed on Sep. 1,2006 and entitled “Auto-focus and zoom module”, which claims priorityunder 35 U.S.C. 119(e) of the co-pending U.S. Provisional Pat. App. No.60/715,533, filed Sep. 8, 2005, entitled “3× zoom module”, both of whichare also hereby incorporated by reference.

FIELD OF THE INVENTION

The invention relates to camera optics, including video optics. Moreparticularly, this invention is directed toward an auto-focus and zoommodule.

BACKGROUND

Recently, there have been numerous developments in digital cameratechnology. One such development is the further miniaturization ofoptical and mechanical parts to the millimeter and sub millimeterdimensions. The reduction in size of the moving parts of cameras hasallowed the implementation of modem digital camera and opticaltechnology into a broader range of devices. These devices are also beingdesigned and constructed into smaller and smaller form factorembodiments. For example, typical personal electronic devices such ascellular phones, personal digital assistants (PDAs), and wrist and/orpocket watches are commercially available that include a miniaturedigital camera. Moreover, larger form factor devices are also packedwith additional features. For example, a typical video camcorder oftenhas an entire digital camera for “still” photography built into thecamcorder device along with the mechanisms and circuitry for motionvideo recording.

Typically, however, modern digital camera implementations suffer from avariety of constraints. Some of these constraints include cost, size,features, and complexity. For instance, with a reduction in sizetypically comes an increase in cost, a reduction in features and/or anincrease in complexity.

SUMMARY OF THE DISCLOSURE

An optical module comprises a first optics group, a second optics group,and an image sensor. The first optics group and second optics group areconfigured to provide an image having a focus and a magnification to theimage sensor.

In some embodiments of the present invention, an optics module comprisesa first optics group that is coupled to a threaded portion of a firstlead screw. Translation of the first lead screw results in translationof the first optics group along an axis of the first lead screw. A firstactuator rotates the first lead screw. A first sensing target isconfigured to permit detection of rotation of the first lead screw. Theoptical module further comprises a second optics group coupled to athreaded portion of a second lead screw. Translation of the second leadscrew results in translation of the second optics group along an axis ofthe second lead screw. A second actuator rotates the second lead screw.A second means for sensing configured to detect translation of thesecond lead screw.

A housing is included in some embodiments to hold the first opticsassembly, the second optics assembly, and the image sensor. The firstoptics group and the second optics group are configured to provide animage having a focus and a magnification to the image sensor. In someembodiments, the first actuator and/or the second actuator areconfigured within an actuator module. Preferably the axes substantiallyparallel to both the first lead screw and second lead screw are parallelto a first guide pin.

Preferably, an actuator module includes a vibrational actuator of thetype that oscillates in a standing wave pattern to drive a threadedshaft placed therein to rotate, thus translating the threaded shaft. Theactuator has a preferred standing wave pattern. The module furtherincludes an actuator housing, with an actuator retention region therein,and a flexible coupling structure. The flexible coupling structure iscoupled to the vibrational actuator at a node point of the preferredstanding wave pattern, and also coupled to the actuator housing. Themodule is coupled with a lead screw comprising a threaded portion, afirst end, and a second end. Specifically, the threaded portion iscoupled to the vibrational actuator.

In some embodiments, the actuator retention region is a five-sidedchamber, with an opening on one side. The opening is sized to fit aparallelepiped containing the vibrational actuator so that a surface ofthe vibrational actuator is parallel with the opening.

Preferably, the first sensing target is configured to permit measurementof translation of the first optics group along the first lead screw andthe second sensing target is configured to permit measurement oftranslation of the second optics group along the second lead screw. Mostpreferably, the first sensing target permits measurement over a range ofat least 10 mm with a resolution of 70 microns or less, while the secondsensing target permits measurement over a range of at least 2 mm with aresolution of less than 10 microns.

The first optics assembly can include a first lead screw which has athreaded portion having a first outer thread diameter, a first end, anda second end. The first optics group is coupled to the first end of thefirst lead screw so that translation of the first lead screw results intranslation of the first optics group along the axis of the first leadscrew. A first vibrational actuator translates the first lead screw,which is constrained at a node point by a flexible coupling to thehousing. The first means for sensing is configured to detect rotation ofthe first lead screw.

The second optics assembly can include a second lead screw, which has athreaded portion, a first end, and a second end. The second optics groupis coupled to the second lead screw so that translation of the secondlead screw results in translation of the second optics group along anaxis of the second lead screw. A second vibrational actuator translatesthe second lead screw and constrained at a node point by a flexiblecoupling to the housing. The second means for sensing is configured todetect rotation of the second lead screw.

Some embodiments of the present invention relate to an auto focus andzoom module that includes a vibrational actuator of the type thatoscillates in a standing wave pattern to drive a threaded shaft placedtherein to rotate, thus translating the threaded shaft. The vibrationalactuator is coupled to a threaded portion of a lead screw and isconstrained at a node point of its preferred standing wave pattern by aflexible coupling with the housing. The vibrational actuator and thelead screw are configured as part of an optics assembly, that alsoincludes an optics group coupled to the lead screw. The coupling betweenthe lead screw and the optics group means that translation of the leadscrew results in translation of the optics group. The assembly furtherincludes a means for sensing configured to detect rotation of the leadscrew. In addition, the module includes an image sensor. The opticsgroup is configured to provide an image having a focus and amagnification to the image sensor. The lead screw of the assembly has afirst end and a second end in addition to the threaded portion.

In some embodiments of the present invention an auto-focus and zoommodule comprises a first guide pin, a second guide pin, a first opticsassembly, a second optics assembly, and an image sensor, wherein thefirst optics group and second optics group are configured to provide animage having a focus and a magnification to the image sensor.

In another aspect, a hard stop is implemented on a body driven along anaxis by threads disposed orthogonal to that axis. The method comprisescoupling a feature to the body to form an assembly having non-symmetricregion relative to the axis. The body is driven by the threads using anactuator. A movable element is coupled to a point fixed relative to theactuator. The movable element has a latch feature configured to matewith the non-symmetric region. The movable element is disposed at aposition such that the latch feature mates with the non-symmetric regionand prevents rotation of the body.

In some embodiments, the step of disposing the movable element isperformed in part by moving the movable element by driving the bodyagainst it. In some embodiments, the feature coupled to the body is acam.

BRIEF DESCRIPTION OF THE DRAWINGS

The novel features of the invention are set forth in the appendedclaims. However, for purpose of explanation, several embodiments of theinvention are set forth in the following figures.

FIG. 1 is an isometric view of an auto-focus and zoom module inaccordance with some embodiments of the invention.

FIG. 2 is an isometric view of an auto-focus and zoom module inaccordance with some embodiments of the invention.

FIG. 3 is an isometric view of internal parts of an auto-focus and zoommodule in an end stop position in accordance with some embodiments ofthe invention.

FIG. 4 is an alternative isometric view of internal parts of anauto-focus and zoom module in end stop position accordance with someembodiments of the invention.

FIG. 5A is an isometric view of internal parts of an auto-focus and zoommodule in a mid position in accordance with some embodiments of theinvention.

FIG. 5B is a plan view of internal spring elements of an auto-focus andzoom module in a mid position in accordance with some embodiments of theinvention.

FIG. 6A is an alternative plan view of internal spring elements of anauto-focus and zoom module in a mid position in accordance with someembodiments of the invention.

FIG. 6B is an isometric view of internal spring elements of anauto-focus and zoom module in a mid position in accordance with someembodiments of the invention.

FIG. 7A is a plan view of internal spring elements of an auto-focus andzoom module in tele position in accordance with some embodiments of theinvention.

FIG. 7B is an isometric view of internal spring elements of anauto-focus and zoom module in tele position in accordance with someembodiments of the invention.

FIG. 8A illustrates an auto-focus and zoom module in an end stopposition in accordance with some embodiments of the invention.

FIG. 8B illustrates an auto-focus and zoom module in a mid position inaccordance with some embodiments of the invention.

FIG. 8C illustrates an auto-focus and zoom module in a tele position inaccordance with some embodiments of the invention.

FIG. 9 is a plan view along the optical axis of an auto-focus and zoommodule in accordance with some embodiments of the invention.

FIG. 10A is a plan view of an actuator assembly in accordance with someembodiments of the invention.

FIG. 10B is an isometric view of an actuator assembly in accordance withsome embodiments of the invention.

FIG. 10C is an isometric view of an actuator assembly in accordance withsome embodiments of the invention.

FIG. 11A is a schematic representation of a rotation sensor inaccordance with some embodiments of the invention.

FIG. 11B is a schematic representation of beam spreading that occursduring sensing in accordance with some embodiments of the invention.

FIG. 11C is a schematic representation of beam spreading that occursduring sensing in accordance with some embodiments of the invention.

FIG. 12A is a schematic illustration of a direct imaging approach forreflecting radiation from a radiation emitter to a detector inaccordance with some embodiments of the invention.

FIG. 12B is a schematic illustration of a lens-based imaging solutionfor collimating radiation from a detector in accordance with someembodiments of the invention.

FIG. 12C is a schematic illustration of a pinhole-based imaging solutionfor preventing ‘bleed over’ in accordance with some embodiments of theinvention.

FIG. 13A is an exploded isometric view of an assembly for positionsensing in accordance with some embodiments of the invention.

FIG. 13B is an exploded isometric view of an assembly for positionsensing in accordance with some embodiments of the invention.

FIG. 14A is a detailed view of a position-sensing portion of an opticalmodule in accordance with some embodiments of the invention.

FIG. 14B is a detailed view of a position-sensing portion of an opticalmodule in accordance with some embodiments of the invention.

FIG. 15 is a detailed schematic of an active area of interface between asensing target and a sensor consistent with some embodiments of theinvention.

FIG. 16 is a schematic representation of a signal produced from asensing target consistent with some embodiments of the invention.

FIG. 17 is a flowchart illustrating a method of sensing a positionconsistent with some embodiments of the present invention.

DETAILED DESCRIPTION

In the following description, numerous details and alternatives are setforth for purpose of explanation. However, one of ordinary skill in theart will realize that the invention can be practiced without the use ofthese specific details. In other instances, well-known structures anddevices are shown in block diagram form in order not to obscure thedescription of the invention with unnecessary detail.

FIGS. 1 and 2 illustrate an auto-focus and zoom module 1000 inaccordance with some embodiments of the invention. The module 1000 isshown with the exterior electro magnetic interference (EMI) shieldremoved.

As shown, the module is built over an image sensor board 10. The module1000 comprises a stiffener 1 disposed on a first side of the imagesensor board 10, and a main structure 20 disposed opposite the stiffener1. Preferably, the stiffener 1 and the main body 20 are coupled with oneanother and with the image sensor board 10.

The main structure 20 comprises a base guide portion 22. The base guideportion 22 includes features configured to retain the guide pins 601 and602. The end guide plate 2 is disposed opposite the base guide portion22. The holes 2 a and 2 b interface with retain the guide pins 601 and602, respectively. The base guide portion 22 further includes a voidregion (not shown) configured to permit passage of radiation, e.g.visible light, through the lens structure of the module (discussedbelow) to the image sensor (discussed below) of the image sensor board10. In addition, the base guide portion 22 includes a pass-thru 25configured to permit the image sensor board extension 11 to passthrough.

Disposed between the base guide portion 22 and the end guide plate 2 arethe remainder of the main body 20 and other components of the module1000. The main body 20 further includes the upper structure 24, and thelower structure 26. Both the lower 26 and upper 24 structures includespecialized features configured to mate with or allow pass-through ofworking components of the module 1000. Thus, the main body 20 providesboth a structure framework and functional support to the workings of themodule 1000.

For example, the lower structure 26 includes the pivot boss 32,configured to act as a fulcrum for the low-variation preload leverassembly (discussed below). In addition, the lower structure 26 includesthe pass through 27, configured to permit movement of the lever assemblythrough a desired range. Similarly, the upper portion 24 includes a passthrough configured to permit coupling between a main PCB and the sensor901 discussed below.

A variety of components of the module 1000 are coupled to the main body20. Some of these components are immobilized relative to the main body20. In addition to the guide pins 601 and 602, the actuator housings1020 and 1030 are coupled to the main body 20 in an immobile position.Thus, the actuator housings 1020 and 1030 are in a fixed positionrelative to the guide pins 601 and 602.

FIGS. 3 and 4 show the internal components of the module 1000. The mainbody 20 (shown in FIGS. 1 and 2) is not shown. As shown in thesefigures, the module 1000 includes a front optics group 400, a rearoptics group 500, and an image sensor 14. The front optics group 400 andrear optics group 500 typically comprise one or more optical elementssuch as a lens group. One of ordinary skill will recognize both complexand simple lens arrangements for the optics groups 400 and 500.

Optionally attached to the main body 20 and the end guide plate 2 is aprism 40, (shown in FIG. 2). The module 1000 preferably further includesa casing and a cover mechanism, as well as an EMI shield as mentionedabove. The cover mechanism preferably prevents light leakage and dustcontamination from affecting the internal components of the module,particularly the lens groups 400 and 500 and the image sensor 14. Insome embodiments, a single external housing functions as both an EMIshield and a cover mechanism. An infrared (IR) filter and/or a low passfilter is optionally attached to the image sensor board 10.

FIGS. 3 and 4 illustrate further details of the module 1000. Asmentioned above, the actuator housings 1020 and 1030 are coupled to themain body 20. This coupling, along with the coupling between the mainbody 20, the end guide plate 2, and the guide pins 601 and 602 positionsand secures the components relative to one another, and to the targetregion 12 of the image sensor 14, providing a chassis for an auto-focusand zoom module capable of providing an image with a magnification andzoom to the target region 12.

Image Sensor

As shown in the figures, the image sensor 14 is substantially planar.The plane of the image sensor is perpendicular to the axes of the guidepins 601 and 701. Typically, the module 1000 is configured to provide animage to the image sensor 14 along an image vector parallel to theseaxes.

Guide Pins

FIGS. 3 and 4 illustrates a guide pin arrangement for an auto-focus andzoom module in accordance with the present invention. Some embodimentsinclude a pair of guide pins, while other embodiments employ a differentnumber of guide pins. Regardless of their number, the guide pins 601 and602 are typically mounted along a linear axis of the module 1000 topermit the rear barrel 530 and the front barrel 430 to move relative tothe image sensor 14. In the module 1000, the primary guide pin 601 andthe secondary guide pin 602 are aligned so that their axes aresubstantially parallel to each other. Further, the lead screw assemblies200 and 300 are also aligned so that their axes are substantiallyparallel to each other, and the guide pins 601 and 602.

Typically, the guide pins 601 and 602 are coupled to the main body 20and the end guide plate 2 as outlined above. Preferably, the guide pinsare coupled on opposite sides of the image vector of the image sensor14. However, one skilled in the art will recognize that otherconfigurations are possible. The lead screws 200 and 300 are typicallydisposed parallel to one another, along an edge of the image sensor 14and parallel to its optical axis.

In some embodiments, the range of motion provided to the rear barrel 530by the guide pins 601 and 602 is approximately 7 millimeters. In someembodiments, the range of motion provided to the front barrel 430 theguide pins 601 and 602 is approximately 2 millimeters. Due to this rangeof motion, however, the guide pins 601 and 602 of some embodiments oftenaffect the form factor of the module 1000. Hence, some embodimentsfurther include means for modifying and/or concealing the form factor ofthe module 1000.

Prism Feature

For instance, some embodiments additionally include a prism feature,e.g. 40 of FIG. 2. This feature allows the auto-focus and zoom module tobe disposed and/or mounted in a variety of orientations. For instance,the dimension available to a particular implementation along the initialdirection of an image vector is often limited such that the module ispreferably disposed lengthwise in the vertical plane of an enclosure.This orientation allows the range of motion of the front and rearbarrels along the guide pins, as described above, to be implemented in adevice having a small width and/or depth form factor. For example, in amobile phone implementation where a user will want to aim a camera at adesired image using the display as a viewfinder, the image vector isadvantageously perpendicular to the display for usability purposes.However, the dimension of the device perpendicular to the display isoften the thinnest dimension of a mobile phone.

Referring to FIGS. 2 and 3, the prism feature 40 of some embodiments ismounted adjacent to the front barrel 430. The prism 40 redirects thelight from an image at an angle with respect to the front barrel 430. Asdescribed above, the front barrel 430 typically houses a front lensgroup. The front lens group contains one or more front optical elements.Hence the prism 100 allows the module 1000 to be disposed in a varietyof orientations within a device that is typically held at an angle withrespect to the subject being viewed and/or photographed.

Lens System

As shown in FIGS. 3, 4 and 5A, the rear optics group 500 and frontoptics group 400 have specialized constructions. The rear optics group500 further includes the rear barrel 530, the rear guide sleeve 510, andthe rear guide slot 520. The rear barrel typically houses one or morelenses or other optical elements. As illustrated, the rear barrel 530houses the rear lens 540. The rear barrel 530 is a substantiallycylindrical body with a central axis. The rear lens 540 is configured todirect light along the central axis of the rear barrel 530. The rearguide sleeve 510 is an elongated, substantially cylindrical body coupledto the rear barrel 530 so that the central axis of the rear barrel 530and an axis of the rear guide sleeve 510 are substantially parallel. Therear guide slot 520 is a slotted feature configured to interface with acylinder.

The front optics group 400 further includes the front barrel 430, thefront guide sleeve 410, and the front guide slot 420. The front barreltypically houses the front lens group 440. The front barrel 430 is asubstantially cylindrical body with a central axis. The front lens group440 is configured to direct light along the central axis of the frontbarrel 430. The front guide sleeve 410 (FIG. 6B) is an elongated,substantially cylindrical body coupled to the front barrel 430 so thatthe central axis of the front barrel 430 and an axis of the front guidesleeve 410 are substantially parallel. The front guide slot 420 is aslotted feature configured to interface with a cylinder.

Lens-Guide Pin Interface

Referring now to FIG. 6B, the front optics group 400 includes the frontguide sleeve 410, which couples with the primary guide pin 601. Asillustrated, the front guide sleeve 410 is substantially elongatedrelative to the front barrel 430. Further, the front guide sleeve 410 isrigidly connected to the front barrel 430. This configuration preventsthe front optics group 400 from rotating around an axis perpendicular tothe axis of the primary guide pin 601, but permits rotation around theaxis of the primary guide pin 601. The rear optics group 500 includesthe rear guide sleeve 510, which also couples with the primary guide pin601. As illustrated, the rear guide sleeve 510 is substantiallyelongated relative to the rear barrel 530. Further, the rear guidesleeve 510 is preferably rigidly connected to the rear barrel 530. Thisconfiguration prevents the rear optics group 500 from rotating around anaxis perpendicular to the primary guide pin 601, but permits rotationaround the axis of the guide pin.

Referring now to FIG. 4, the front optics group 400 also includes thefront guide slot 420, configured to couple with the secondary guide pin602. The coupling between the guide slot 420 and the secondary guide pin602 prevents the front optics group 400 from rotating around the axis ofthe primary guide pin 601. The coupling between the front optics group400 and guide pins 601 and 602 permits the front optics group 400 totranslate along an axis substantially parallel to the two guide pins.

The rear optics group 500 also includes the rear guide slot 520,configured to couple with the secondary guide pin 602. The couplingbetween the guide slot 520 and the secondary guide pin 602 prevents therear optics group 500 from rotating around the axis of the primary guidepin 601. The coupling between the rear optics group 500 and guide pins601 and 602 permits the rear optics group 500 to translate along an axissubstantially parallel to the two guide pins.

Actuator Modules

Preferably, the actuators used within embodiments of the presentinvention are vibrational actuators. Most preferably, these vibrationalactuators are of the type that oscillates in a standing wave pattern todrive a threaded shaft placed therein to rotate, thus translating thethreaded shaft. Embodiments of the present invention include certainpreferred standing wave patterns for driving the vibrational actuators.However, a variety of standing wave patterns are contemplated.

The present invention contemplates a variety of actuator constructions.These include vibrational actuators as disclosed in U.S. Pat. No.5,966,248 issued Oct. 12, 1999 and U.S. Pat. No. 6,940,209 issued Sep.6, 2005. These also include actuators as shown for example in FIGS. 10Ato 10C. The actuator 700′ comprises a flexible body surrounded by aplurality of piezoelectric strips, 701, 702, and 704. A fourth strip,not shown, is disposed opposite the strip 701. The strips are arrangedsymmetrically around a flexible body that has a plurality ofthread-interface features disposed therein. The thread interfacefeatures are configured to mate with the threads of the lead screw 360′.During operation, the piezoelectric strips drive an oscillating motionwithin the flexible body. Actuators of this type typically require anoperating preload. Preferably, this preload is applied to the lead screwvia techniques disclosed elsewhere in this document.

In order to effectively drive a threaded shaft by using the preferredvibrational actuators, some embodiments of the present invention includespecialized actuator housings, designed to constrain the actuator toonly the degree necessary and also to provide shock protection for theactuator. In addition, the actuator housings permit close positioning ofactuator relative to the guide pin and optics group. Typically, eachactuator within the embodiment is combined with an actuator housing toform an actuator module.

Some embodiments of the present invention include actuator modules suchas those illustrated in FIGS. 10A to 10C. A typical actuator module, asillustrated, includes an actuator 700′, an actuator housing 1030′, and aflexible coupling 710.

The flexible coupling 710 constrains a portion of the actuator 700′ to asubstantially fixed position relative to the actuator housing 1030′.This permits the actuator to drive a lead screw to translate relative tothe actuator housing 1030′. For example, the contact pads 710 preventthe actuator 700′ from rotating relative to the housing.

However, by constraining only a portion of the actuator 700′, theembodiment permits relatively free vibration of the actuator 700′ toimpart movement to a lead screw, e.g. 360′. Further, because theflexible coupling 710 preferably constrains the actuator 700′ at a nodepoint of the preferred standing wave pattern of the actuator 700′, theeffect of the constraint on the efficiency of the actuator is reduced.Preferably, the fixed location is chosen to be a node point of a varietyof standing wave patterns, thus permitting efficient operation of theactuator under a variety of conditions.

As illustrated, the actuator housing 1030′ includes openings 1034 and1036 to admit the lead screw 360′. In addition, the housing includesopenings 1032 and 1038 configured to admit electrical connections to amain PCB board (not shown). In addition, the actuator housing 1030′ isspecialized to prevent shock damage to the actuator 700′. The actuatorhousing 1030′ is preferably a five-sided chamber that forms aparallelepiped therein. This parallelepiped, called the actuatorretention region, is larger in volume than the actuator 700′. Further,the actuator retention region is larger along every dimension than thecorresponding dimension of the actuator 700′. In addition, when theactuator 700′ is constrained within the actuator retention region by theflexible coupling 710, preferably a surface of the actuator 700′ isparallel with the surface of the parallelepiped that does not include aportion of the actuator housing. Further, the ends of the actuator 700′are preferably approximately equidistant from the openings 1034 and1036, respectively. Thus, the actuator 700′ is suspended within theretention region with a buffer distance between it and each adjacentsurface of the actuator housing 1030′.

Further, the size of the parallelepiped actuator retention region andthe actuator 700′ are matched to one another, and to the type offlexible coupling 710 used to retain the actuator. Preferably, thebuffer distance between the actuator 700′ and the inner surfaces of thehousing 1030′ adjacent to the openings 1034 and 1036 are chosen relativeto the maximum displacement permitted prior to failure by the flexiblecoupling 710. Thus, during a mechanical shock, the actuator 700′ willencounter an inner surface of the housing 1030′ prior to stretching theflexible coupling 710 to failure. In addition, similar stretching alongaxes perpendicular to the lead screw 360′ is prevented by the couplingbetween the lead screw 360′ and the actuator 700′.

The actuator housings 1030 and 1020 permit close positioning ofactuators 700 and 500 relative to the primary guide pin 601. As shown inFIG. 9, this close positioning is permitted because the open end of theactuator housings 1020 and 1030 allow the actuators 500 and 700 to bedisposed at a surface of the actuator module. Thus, the actuators 500and 700 are placed proximate to the primary guide pin 601, leavingclearance for the guide sleeves 410 and 510.

Close positioning increases precision by minimizing torque effects asthe actuators 200 and 300 drive the optics modules 400 and 500,respectively. The center of mass of the optics modules 400 and 500 liesbetween the guide pins 601 and 602. The lead screw coupling surfaces 480and lie off center. Thus, driving the optics modules 400 and 500 by thecoupling surfaces 480 and 570 tends to introduce a torque. The guidepins, including the primary guide pin 601, counteract the torque effect.However, configuring the modules so that the actuators 500 and 700, andthe coupling surfaces, are nearly aligned with the guide pin 601 reducesthe amount of torque on the guide pins.

Lead Screw Assemblies

Referring now to FIGS. 10A to 10C, the exemplary lead screw assembly300′ is shown coupled with the actuator housing 1030′. The lead screwassembly 300′ is structured around the lead screw 360′. The assemblyincludes cam 320′ and the referencing cap 340. The lead screw 360′comprises a threaded region 5, a first end, and a second end. The firstend of the lead screw 360′ and the referencing cap 340 are integrallyformed.

Lead screw-Optics Group Interface

Referring now to FIG. 8A, the front optics group 400 and rear opticsgroup 500, respectively, couple with the lead screws through the leadscrew coupling surfaces 480 and 570 respectively. Both primary guidesleeves 410 and 510 couple with the primary guide pin 601.

In the preferred configuration, movement of a lead screw transmits forcethrough its counterpart lead screw coupling surface. Since the couplingsurfaces are each a rigidly coupled component of an optics group,translation of a coupling surface results in translation of itscounterpart optics group. However, a simple rigid connection between acoupling surface and a lead screw could accomplish this function. Theillustrated configuration provides additional benefits by isolating theoptics group from non-translational movements of the lead screw.Preferably, a reference cap coupled to the first end of a lead screwcontacts the coupling surface, for example, see the reference cap 340 ofFIG. 10C.

The small contact area between the reference cap and the couplingsurface serves to minimize friction, permitting movement of the couplingsurface relative to the reference cap and the lead screw in the axesorthogonal to the axis of the lead screw. This configuration isolatesmost mechanical vibration or disturbance of the lead screw from theoptics group. Further, the isolation means that only the translationaldegree of freedom of the lead screw need be controlled to achieve arequired precision for positioning of the optics group. Thoughnon-translational movement of the lead screw is not present in thepreferred embodiment, these features permit embodiments of the presentinvention to deal with this type of wobble when present.

To maintain coupling between a coupling surface and lead screw, someembodiments of the present invention rely on preload springs otherwiserequired for accurate operation of the actuators.

Preload Springs

In addition to the features mentioned above, the actuators used withinembodiments of the present invention typically require a low-variationpreload force. This preload is provided by a spring with a low forceconstant. In small displacement implementations this method works well.

Some embodiments of the present invention rely on spring forces actingon the optics groups to provide preload to the lead screws used to drivethe groups. Thus, to an extent, the required displacement of the opticsgroup determines the type of spring force transmission mechanismrequired.

For example, in some embodiments of the present invention the frontoptics group 400 is used for focusing and zoom operations and need onlybe displaced a millimeter or two. Because the preferred range of motionof the front optics group 400 is less than two millimeters, choosing alow force constant spring for the spring and coupling it to directlyexert spring forces on the optics group results in a relatively lowvariation preload.

As illustrated in FIG. 8B, the front lead screw coupling surface 480 isadjacent to the first end of the lead screw 260. To couple the surfacewith the lead screw and provide preload, the preload spring must urgethe surface against the lead screw. Because of the small movementsinvolved in focusing, directly providing the spring force is permissiblein this case. Thus, the front preload spring 180 is coupled to the frontoptics group 400 via the preload interface feature 470 (FIG. 6B) andconfigured to directly exert force on the optics group 400.

In another example, the rear optics group 500 is used for zoomoperations and need be displaced several millimeters or more. Becausethe preferred range of motion of the front optics group 500 is more thanfour millimeters, choosing a low force constant spring for the springand coupling it to directly exert spring forces on the optics groupresults to high a variation in preload.

As illustrated in FIGS. 6A and 6B, the rear lead screw coupling surface570 is adjacent to the lead screw 360. To couple the surface with thelead screw and provide preload, thus preload spring must urge thesurface against the lead screw. However, direct provision of the preloadis undesirable in this case.

Thus, the preload spring 110 is configured on the opposite end of apreload lever 100. The zoom preload lever 100 includes a pivot hole 140configured to mate with the pivot boss 32 of the main body 20. Inaddition, the preload lever 100 includes a preload spring hook 130 and apreload force transfer point 120.

The pivot hole 140 is skewed toward the preload spring hook 130 so thatmovement at the hook end of the preload lever 100 is amplified at theforce transfer point end. By the same mechanism, large movements at theforce transfer point 120 end of the zoom lever 100 translate intorelatively smaller movements at the spring hook 130 end. Preferably, thelocation of the pivot hole 140 is chosen to decrease the travel from theforce transfer end to the spring hook end, in this example by a factorof five. Other embodiments employ a different factor.

The spring hook 130 is coupled with the preload spring 110, and theforce transfer point 120 is coupled with one face of the rear lead screwcoupling surface 570. The coupling surface 570 is also adjacent to thelead screw 360. To couple the surface with the lead screw and providepreload, the preload spring must urge the surface against the leadscrew. Indirectly providing the spring force from the rear preloadspring 110 through the lever 100 means that travel of the rear opticsgroup 500 translates indirectly into extension of the preload spring110. The specific proportionality of group travel to spring extensiondepends on the positioning of the lever pivot relative to the forcetransfer point and spring hook. As described above, the preferred ratiois one-fifth.

In either case, indirect or direct preload spring force application, theopposite end of the preload spring is preferably coupled to the mainbody 20.

Sensing Target

Some embodiments of the present invention include sensing targets toprovide feedback on positioning. In some embodiments, a sensing targetis disposed on a lead screw. In some embodiments, a sensing target isdisposed on an optics group. Both linear and rotational targets can beused with the present invention.

A lead screw assembly in accordance with some embodiments of the presentinvention includes a sensing target. Some lead screw assemblies, such asthe assembly 300′ of FIG. 10A to 10C, do not include a sensing target.However, the lead screw assembly 200, shown for example in FIG. 8C,includes the sensing target 290 positioned adjacent to the cam 220. Inthe illustrated embodiment, the target 290 is a rotational target. Theuse of a rotational target is preferred in contexts that require veryfine positioning.

Typically, a sensing target adapted for coupling to a lead screwincludes a feature that interfaces with a registering feature of leadscrew. In some embodiments the sensing target interfaces with thethreads of a lead screw. The position sensing target 290 is configuredto engage with the position sensor 902.

In some embodiments, a sensing target is included as part of an opticsgroup. For example, in FIGS. 8A to 8C, the sensing target 590 isconfigured as part of the rear optics group 500. Here, the target 590 isconstructed as an integral part of the optics group 500. However, insome embodiments, a sensing target is modular, or merely coupled with anoptics group.

In addition, the sensing target 590 is a linear sensing target. Lineartargets are acceptable in relatively low precision positioningapplications. Further, linear targets are preferred in applicationswhere the target need move over a relatively large range. Here, thelinear target is employed in the rear optics group 500 because the groupis used for zoom purposes.

In FIG. 8A the module is in an end stop position. In some embodiments,the position sensors 901 and 902 are disengaged from the sensing targets590 and 290, respectively, during end stop. In this position, alsoillustrated in FIGS. 3 and 4, the lead screw positions are registered ata mechanical hard stop via means discussed elsewhere in this document.Thus, because in these embodiments the lead screw positions correlatewith the optical group positions, the registering of the lead screwsdefines the position of the optical groups as well.

In FIGS. 8B and 8C, the modules are in mid position and tele position,respectively. Preferably, the sensing targets 590 and 290 are engagedwith the position sensors 901 and 902, respectively, while in mid andtele position. Preferably, the position sensors and sensing targets areengaged throughout all zoom positioning.

Mechanical Hard Stop Latch

Preferably, embodiments of the present invention include featuresconfigured to permit referencing of the optics group via a mechanicalhard stop.

Referring now to FIGS. 3 and 4, these embodiments include the hard stoplatch spring 310 and the hard stop latch spring 410. The hard stop latchspring 310 is mounted to the main body 20 on the spring boss 21. Asshown in FIGS. 3 and 4, the hard stop latch spring 310 comprises asubstantially rigid body and an active spring 312. The rigid bodyincludes the lens group interface surface 314, the pivot hole 318, andthe latch 316. The lens group interface surface 314 and the latch 316are each arranged on separate arms positioned approximately 90 degreesapart around the pivot hole 318, and extending outward therefrom. Thelatch 316 arm is substantially longer than the group interface surface314 arm. At rest the active spring 312 is aligned with the latch 316arm.

The pivot hole 318 is mated with the spring boss 21 and configured topivot around the boss 21. The group interface surface 314 is configuredto mate with the spring driver 580 of the rear lens group 500. At rest,the latch 316 is disposed out of line with the actuator housing 1030,e.g. FIG. 5A. The hard stop latch spring 310 pivots around the hole 318when the spring driver 580 urges the group interface surface 314 towardthe image sensor, flexing the active spring 312. When pivoted, the latch316 moves into place to interface with the cam feature 322 of the cam320. This provides a mechanical hard stop for the lead screw 360.

The hard stop latch spring 210 is mounted to the actuator housing 1020on the spring boss 1028, as shown in FIG. 5B. The hard stop latch spring210 comprises a substantially rigid body and an active spring 212. Therigid body includes the lens group interface surface 214, the pivot hole218, and the latch 216, e.g. FIG. 4. The lens group interface surface214 and the latch 216 are each arranged on separate arms positionedapproximately 90 degrees apart around the pivot hole 218, and extendingoutward therefrom. The latch 216 arm is substantially longer than thegroup interface surface 214 arm. At rest the active spring 212 isaligned with the latch 216 arm.

The pivot hole 218 is mated with the spring boss 1028 and configured topivot around the boss 1028. The group interface surface 214 isconfigured to mate with the spring driver 480 of the front lens group400. At rest, the latch 216 is disposed out of line with the actuatorhousing 1020, e.g. FIG. 5A. The hard stop latch spring 210 pivots aroundthe boss 1028 when the spring driver 480 urges the group interfacesurface 214 toward the image sensor, flexing the active spring 212. Whenpivoted, the latch 316 moves into place to interface with the camfeature 222 of the cam 220. This provides a mechanical hard stop for thelead screw 260, e.g. as shown in FIG. 8A.

Position Sensing

Embodiments of the present invention include position-sensing elementsconfigured to provide feedback to an actuator control system. Theseelements permit the module to accurately position functional groups,e.g. optics, by using non-linear actuator motors.

Preferred embodiments of the present invention employ a sensing targetthat moves in concert with a functional group of the module, and asensor configured to detect and encode data representing movement of thesensing target. For example, some embodiments use reflection encoding ofa mobile sensing target that comprises regions of differing reflectance.An exemplary position sensing system comprises the position sensors 1030and the position sensing targets 250 and 350 of the module 1000 of FIG.1.

Reflection Encoding

In the exemplary reflection encoding system, a sensor includes anelement that emits radiation and an element that detects radiation. Atarget includes dark and light bands, for example. The dark bands tendto absorb a greater proportion of the emitted radiation than do thelight bands. The radiation reflected by the bands is detected by thesensor. As the target moves relative to the sensor, the absorption andreflectance of the sensing target portion aligned with the sensorvaries. The sensor encodes this variation. A variety of encodingalgorithms and processes are consistent with the present invention. Forexample, a sensor could simply detect each transition between a dark andlight band.

System Resolution

The resolution of a reflection encoding system is determined by severalfactors. The distance between the emitter/detector and the target, thebeam spread of the radiation used, and the native target resolution allplay important roles in determining a system's resolution. These threefactors do not act separately, rather they interact, and each must betuned relative to the others.

Native target resolution is essentially a function of feature size. Thesmaller the critical dimension—the dimension parallel to sensormovement—of a target's features, the greater its native targetresolution. For example the target 250 of FIG. 1 uses stripe pairs asfeatures. The sensing system is configured to move stripes along theirnarrow dimension across a sensor's field of view. Thus a criticaldimension of a stripe pair in the illustrated configuration is its widthalong the narrow dimension.

However, a position sensing system does not guarantee high resolutionsimply by using a high native target resolution. A suitable combinationof low beam spread radiation and tight emitter-target tolerances isrequired to achieve a maximal resolution permitted by a given featuresize. The beam spread and tolerance specifications are complementary: adecrease in beam spread combined with an appropriate increase intolerance can maintain a given resolution, and vice versa.

For a given feature size, there is a maximum radiation beam spread abovewhich the features are not resolvable via reflection encoding. FIG. 11Billustrates the maximum beam spread for a series of light sources (whitesquares on left hand side) emitting light towards a series of absorptiveand reflective bands (right hand side). The detail shown in FIG. 11Cillustrates a 20-micron wide light source paired with a target havingsimilarly-sized features. In this case, the maximum tolerable spread is10 microns.

Under set diffusion conditions, the maximum tolerable spread and desiredresolution determine a maximum spacing between a radiation source andthe target. This spacing, distance d in FIG. 11C, is proportional to therequired resolution, and inversely proportional to the tangent of anangle representing the diffusion of the radiation. For example, given atypical LED diffusion angle of 30 degrees, to achieve 10 micronresolution the distance d should be less than 56.7 microns. Thus, toachieve the native target resolution, a suitable combination of beamspread radiation and spacing should be employed.

Native Target Resolution

Some embodiments of the present invention employ position sensingsystems with beam spread and tolerance optimized to operate at nativetarget resolution. In reflection encoding, a variety of methods,strategies, and devices are available to achieve this goal.

FIG. 12A illustrates a direct imaging approach where a radiation emitter(white rectangle), e.g. an LED, produces radiation which is supplied tothe target without additional processing. A portion of the radiationreflecting from the target is detected by a detector (hatchedrectangle). In this type of approach, the emitter must produce radiationwith a sufficiently low beam spread to resolve the target features.

Tolerances

One method of achieving native target resolution is closely spacing theemitter/detector and the scanning target. However, tightening tolerancesincreases the precision required in manufacturing both the target, andthe device as a whole. For example, the cross-sectional roundness of acylindrical target becomes increasingly important as the spacingdecreases. For these and other reasons, embodiments of the presentinvention preferably space the emitter/detector and scanning target atdistances achievable within tolerances typical of mass-manufacturing.

Active Area—Emitter/Detector Modification

Several combinations of features and methods can be employed to lessenthe spacing requirements tolerances or decrease problems caused bydiffusion of the radiation. In reflection encoding, a portion of thesensing target is excited by radiation and a detector receives a signalfrom the sensing target. The signal received represents thecharacteristics of an active area of the sensing target. Preferably, theactive area is sized and located to match critical feature dimensions ofthe sensing target. For example, FIG. 15 illustrates the active area ofa sensing target.

The size and location of the active area are determined bycharacteristics of both the emitter and the detector. In some cases, theradiation is conditioned to limit the portion of the sensing targetexcited by radiation. In some cases, the field of view of the detectoris cropped.

Some techniques involve radiation processing measures that permit theuse of higher resolution targets at manufacturable spacings than wouldbe possible using more diffusive radiation. FIG. 12B illustrates asystem in which a lens is used to collimate radiation from a detector.Collimating the radiation permits target-sensor spacing to increaserelative to direct imaging while maintaining ability to resolve a setfeature size. The maximum spacing and resolvable feature sizes aredetermined by the spreading of the radiation following collimation.

Some techniques involve elements configured to limit the field of viewof a sensor to a portion of its native field of view. FIG. 12Cillustrates a system in which a pinhole is used to prevent ‘bleed over’from an adjacent region from preventing detection of a transition. Inthis case, reflected radiation must pass through the centered pinholeplaced near to the target surface before reaching the detector. Thissystem can require higher intensity emitters, as relatively littleradiation is available through the pinhole.

Though certain embodiments of the present invention do employ activearea cropping strategies, such as radiation conditioning, the additionaldevices or features needed to carry out these strategies increases thecost and complexity of the manufactured module. Preferably, embodimentsof the present invention employ other means to achieve desiredresolutions.

Beyond Native Target Resolution

At certain thresholds, achieving high system resolution though use ofhigh native target resolution begins to necessitate radiationconditioning or tight spacing. As outlined above, these elementsincrease the complexity of a module and the precision required inmanufacturing. Therefore, for resolutions above these thresholds,embodiments of the present invention preferably employ a lower nativetarget resolution combined with at least one of a variety of strategiesfor achieving system resolution greater than native target resolution.

Active Area—Target Modification

The methods of defining an active area referred to above relate toconditioning radiation from an emitter, selecting a detector with anappropriate field of view, or modifying the field of view using anexternal device. However, alternative methods relate to configuring thesensing target to limit the portion thereof excited by radiation at anyone time, and thus cropping the active area.

For example, the cross-sectional view of FIG. 11A illustrates aconfiguration in which the feature size is paired with arc of acylindrical sensing target to limit the field of view of a detector. Thefield of view of the emitter/detector 3030 subtends a region of thetarget 3350 that includes a maximum of two transitions.

Preferably, the sensing target and detector are configured such that asingle feature dominates the field of view. For example, as illustratedin FIG. 15, an active area is sized to match the width of a stripe pair.Typically, the feature size of the target is chosen based on the fieldof view. However, the required resolution can also be a factor indetermining feature size.

Data Processing

Preferably, embodiments of the present invention process data from asensor to achieve resolutions higher than native target resolution. Avariety of processing techniques, methods and elements are employedwithin various embodiments of the invention, including threshold-basedsignal conversion and interpolation.

Preferably, embodiments of the present invention encode a portion of thesensing target within the active area into an voltage. The voltagevaries depending on the character of the portion of the sensing targetwithin the active area at time of encoding.

Embodiments of the present invention preferably match the dimensions ofthe active area to the critical dimensions of the sensing targetfeatures in order to produce a smoothly varying signal. FIG. 15illustrates a preferred relationship between the active area and sensingtarget feature dimensions. The active area is sufficiently large alongthe direction of the critical dimensions so that it will notsequentially encounter regions with the same light/dark characteristics.In the illustrated embodiment, along the critical dimension the activearea is larger than one feature's width and smaller than twice thatwidth. This type of configuration substantially prevents ‘flat’ spotsfrom occurring within the analog signal produced.

Over time, as the sensing target moves through the active area, thesystem forms a signal representing the portions of the sensing regionthat have passed through the area. As shown in FIG. 16, a sensingtarget, part 1, and a varying signal, part 2, are correlated along atime axis t. The strength of the signal in part 2 at a given point intime is determined by the characteristics, e.g. the proportion of lightand dark stripe, within the active region at that time. As illustrated,the minima of the signal in part 2 correspond in time to the centralaxes of the dark stripes. Similarly, the maxima of the signal in part 2correspond in time to the central axes of the light stripes.

In some embodiments the signal is a continuous encoding of the voltage,in other embodiments the signal is a series of discrete samples taken ata particular frequency. In either case, the signal preferably containsmultiple samples related to each feature of the sensing target as itmoves across the sensor's field of view.

The encoding process produces a variable signal representing themovement of the sensing target. The minima and maxima of the signalrepresent movement of the sensing target at its native targetresolution. Preferably, this variable signal is an analog voltage. Insome embodiments, interpolation is used to construct higher resolutiondata between the minima and maxima of the variable signal. Preferablythe interpolation error occurs only within a given period of the nativetarget resolution and is reset with each minimum or maximum of thesignal. This limits the error introduced by interpolation to asubstantially fixed percentage of the native resolution.

A processing system receives a variable signal from the sensor andproduces corrected movement data at a resolution higher than nativetarget resolution. For example, in some embodiments, the analog voltagesignal is supplied to an analog to digital converter (ADC). The analogsignal, which was produced at a sampling rate that results in multiplesamples per feature, contains sufficient information to support ADCproduction of digital signal with a resolution greater than nativetarget resolution. In some embodiments, an ADC process using multiplethresholds is used to encode an analog signal to a higher-resolutiondigital signal.

The corrected movement data is then translated into position data whichrepresents the position of a functional group coupled to the sensingtarget. For example, in some embodiments digital data from the ADC issupplied to a controller where it is analyzed and translated intoposition data.

One method in accordance with the present invention is illustrated inFIG. 17. The method seeks to detect a position of a functional groupcoupled to a sensing target configured to represent movement of thefunctional group a first resolution. It comprises a step 5010, of usingthe sensing target to detect movement of the functional group at thefirst resolution. The method further comprises a step 5020, of encodingraw movement data representing the detected movement. In another step5030, the method comprises processing the raw movement data intocorrected movement data having a second resolution, wherein the secondresolution is greater than the first resolution. Further, the methodincludes a step 5040, of translating the corrected movement data intoposition data representing the position of the functional group.

Preferably, embodiments include additional calibration of processingcircuitry. In the preferred embodiment, an initial calibration isaccomplished automatically during power on. For example, in an ADC-basedsystem, self-calibration during power-on preferably determines the inputrange needed for data. Embodiments that use self-calibration do notrequire initial calibration during manufacturing or storage of fixedcalibration parameters over their lifetime. In addition, the calibrationpreferably defines the initial position for each functional group. Insome embodiments, these initial positions are determined by a hardreference stop discussed elsewhere in greater detail. In someembodiments, the positions are determined via information embedded intothe sensing target. In some embodiments, position is referenced by theabsence of interaction between the sensor and sensing target.

Specifically, referring to FIG. 14A, as the rear barrel 530, sensingtarget 590 and guide sleeve 510 move along the guide pin 601, thesensing target 590 and the sensor 901 eventually become disengaged. Atthis point the signal read by the sensor 901 changes, permitting thesystem to reference the location of the sensing target 590, the rearbarrel 530, or the rear lens (not shown). In addition, during the samemovement, the spring driver 580 contacts the lens group interfacesurface 314 of the hard stop latch spring 310, eventually reaching amechanical hard stop, which can also be used as a reference as describedabove.

Referring now to FIG. 14B, a similar process can be employed for thefront lens position sensor. The front sensing target 290 and the sensor902 eventually become disengaged during movement of the front lead screw260. At this point the signal read by the sensor 902 changes, permittingthe system to reference the location of the front sensing target 290, orthe front lens (not shown). In addition, during the same movement, thecam feature 222 of the cam 220 contacts the lens group interface surface216 of the hard stop latch spring 210, eventually reaching a mechanicalhard stop, which can also be used as a reference as described above.

However, some embodiments also include continuous calibration duringsensing to handle signals with noisy time-variance. A variety ofconfigurations produce signals with slight instabilities over time. Forexample, FIG. 16, part 3 illustrates a signal with an average magnitudethat ‘wobbles’. A variety of design and manufacturing decisions mayresult in such signals, for example off center mounting of a cylindricalsensing target. In some embodiments a calibration constant correlated toinstabilities is used to counteract them and dynamically correct theprocessing output. For example, the average magnitude over a trailingtime or frequency period.

In some embodiments, non-volatile memory elements are included in thecontrol or processing circuitry and used to provide additionalmanufacturing and calibration data. Preferably, this additional data isused to adjust for component variation and manufacturing tolerances.

Some embodiments that employ interpolation use additional hardwareand/or firmware (e.g. a clock for timing and for analysis). If theactuator is very non-linear, interpolation can introduce positioningerror. Preferably, embodiments of the present invention use ADCtechniques.

Configurations

Embodiments of the present invention include position sensing systemsthat employ a variety of different configurations of sensors and sensingtargets. Some embodiments include cylindrical sensing targets, closedsurfaces configured to rotate along with a lead screw or otherrotational drive mechanism. Since the functional group is coupled withthe lead screw, which has known thread pitch, lead screw rotation isproportional to translation of the functional group along the lead screwaxis. In addition, some embodiments include linear sensing targetscoupled to a functional group and configured to move therewith. Thesensing systems discussed in the examples below are illustrated withcylindrical sensing targets; however, the methods, strategies andequipment described are also contemplated for use with linear targetswithin some embodiments of the present invention.

For example, a system employing a rotational sensing target isillustrated in FIG. 11A. As shown by the cross sectional view, aposition sensing system includes the cylindrical target 3350 positioneda distance d from the emitter/detector 3030. The field of view of theemitter/detector 3030 subtends a region of the target 3350 that includesa maximum of two transitions. In some embodiments the emitter/detectoris a photoreflector.

In another example, illustrated in FIG. 13B, an emitter/detector 4030comprises a sensor 4034, and an emitter 4032. The emitter/detectorfurther includes a mask structure 4030′ includes the emitter window4032′ and the two sensor windows 4034′ and 4034″. In some embodimentsthe emitter is an LED.

The dark bands of the sensing target 4350 absorb radiation emitted fromthe emitter, while the light bands of the sensing target reflectradiation emitted from the emitter. The sensors detect transitions inabsorption and reflectance as the bands move relative to the sensorwindows. Preferably, the sensor 4034 separately detects transitions inboth sensor windows 4032′ and 4034″. In some embodiments theemitter/detector 4030 is a photoreflector.

In yet another example, illustrated in FIG. 13A, an two-detector moduleis employed. The emitter/detector 3030 comprises a first sensor 3034A, asecond sensor 3034B, and an emitter 3032. The mask structure 3030′includes the emitter window 3032′ and the four sensor windows 3034A′,3034A″, 3034B′, and 3034B″. In some embodiments, the emitter/detector3030 is a photoreflector. In some embodiments the emitter is an LED.

Radiation from the emitter 3032 is substantially absorbed by dark bandsand substantially reflected by the light bands of the sensing target3350. The sensors 3034A and 3034B detect transitions in absorption andreflectance as the bands move relative to the sensor windows. Both thefirst sensor 3034A and the second sensor 3034B detect transitions.

In some embodiments, a detector encodes a given transition at differentpoints in time. In addition, in some embodiments, a detector includesmeans for encoding a transition in two data forms that differ by aconstant, such as a phase. In some embodiments, e.g. FIG. 13A, twoseparate sensors encode transitions out of phase of one another. Inother embodiments, a single sensor views transitions at two differentpoints in space, e.g. the two windows 3034′ and 3034″ of FIG. 13B.Preferably, in these embodiments a control system combines theout-of-phase data, permitting it to detect a direction of movement aswell as its magnitude.

In a cylindrical sensing target within the above configurations, eachfeature preferably covers 60 degrees of the circumference. Thus, in oneembodiment, a cylindrical target having a 12 mm circumference includessix 2 mm stripes in an alternating reflective/absorptive pattern. Inaddition, processing steps as outlined above are preferably employed toincrease resolution above that offered natively by this type of target.

A position sensing system provides position data for a lens group overits range of motion. In some embodiments of the present invention, aposition sensing system tracks the relative position of an optics groupto within 70 microns over a range of 10 mm.

Operation

Preferred systems employ the position sensor data to control anactuator. In some embodiments, the data is used to predict the movementper cycle of the actuator. In some embodiments, the data is used topredict the movement per unit time that the actuator is engaged andpowered on. In some embodiments, the data are used on a real-time basiswith a correction cycle for increased accuracy. Preferably, theparticular implementation used is determined in accordance with theparticular actuator used.

Some embodiments of the present invention use the position data duringzoom and auto-focus operation to accurately position and track opticsgroups. Preferably, during zoom operation, multiple lens groups aremoved and tracked. The actuator control circuitry preferably accuratelyinterprets position data to accomplish tracking and movement. In someembodiments, the control circuitry uses tracking interpretation datathat is stored in a table. In some embodiments, the control circuitryuses tracking interpretation data that is stored as a mathematicalfunction. Sometimes, this data is defined in a calibration cycle.Preferably, this calibration cycle takes place during manufacturing.

In addition, the actuator control circuitry preferably accomplishes zoomoperations within a specified time frame. Preferably, in embodimentsthat relate to video optics, the zoom operations are accomplished in amanner that does not disturb video recording. In some embodiments, thezoom range and frame rate are used to determine an optimal step size.For example, the total zoom range is divided by the number of frameswithin the desired seek time to yield the step size. Thus, each step canoccur within a frame. Preferably, when zoom operations occur, the stepsare synchronized with the frame rate. In addition, the movement ofmultiple groups during zoom operations is preferably interleaved. Thus,as each group is moved, the remaining groups are stationary.Interleaving reduces driver and instantaneous power requirements.

In addition, during auto focus operation, typically a single group ismoved. Preferably, a group is moved through a focus range in smallincrements. Preferably, an accurate position sensor and actuator controlcircuit is employed to permit s positioning in increments below 20micrometers. In addition, though a variety of circuitry and hardware canbe used to implement the auto-focus algorithm, preferred implementationspermit reliable return of the group to the position that shows bestfocus.

As described above, the optical elements of some embodiments are dividedinto two groups, one group housed in a front barrel, the other grouphoused in a rear barrel. Typically, the precise motion of these opticsgroups group within confined spaces is achieved by using themechanism(s) described above.

The form factor of the auto-focus and zoom module of some embodiments isapproximately 9×14×22 mm without a prism or approximately 9×14×30 mmincluding a prism.

While the invention has been described with reference to numerousspecific details, one of ordinary skill in the art will recognize thatthe invention can be embodied in other specific forms without departingfrom the spirit of the invention. Thus, one of ordinary skill in the artwill understand that the invention is not to be limited by the foregoingillustrative details, but rather is to be defined by the appendedclaims.

1. An optical module, comprising: a) a first optics group coupled to afirst lead screw so that translation of the first lead screw results intranslation of the first optics group along an axis parallel to thefirst lead screw; b) a first actuator for translating the first leadscrew; c) a first sensing target configured to permit detection oftranslation of the first lead screw; d) a second optics group coupled toa second lead screw so that translation of the second lead screw resultsin translation of the second optics group along an axis parallel to thesecond lead screw; e) a second actuator for translating the second leadscrew; f) a second sensing target configured to permit detection oftranslation of the second lead screw; and g) an image sensor.
 2. Themodule of claim 1, wherein the first optics group and second opticsgroup are configured to provide an image having a focus and amagnification to the image sensor.
 3. The module of claim 1, wherein theimage sensor is selected from the group consisting of: complementarymetal oxide semiconductor (CMOS), and a charge-coupled device (CCD). 4.The module of claim 1 further comprising a prism element coupled to thefirst optics group, wherein the prism directs to the first optics groupan image that is at an angle with respect to a plane of the module. 5.The module of claim 1, wherein the first sensing target is configured topermit measurement of translation of the first optics group along thefirst lead screw.
 6. The module of claim 5, wherein the first sensingtarget permits measurement of translation of the first optics group overa range of at least 10 millimeters with a resolution of 70 microns orless.
 7. The module of claim 1, wherein the second sensing target isconfigured to permit measurement of translation of the second opticsgroup.
 8. The module of claim 7, wherein the second sensing targetpermits measurement of translation of the second optics group over arange of at least 2 millimeters with a resolution of 10 microns or less.9. The module of claim 1, wherein both the axis substantially parallelto the first lead screw and the axis substantially parallel to thesecond lead screw are parallel to a first guide pin.
 10. An auto-focusand zoom module, comprising: a) a housing; b) a first optics assembly,comprising: i) a first lead screw including a threaded portion, a firstend, and a second end ii) a first optics group coupled to first end ofthe first lead screw so that translation of the first lead screw resultsin translation of the first optics group along an axis of the first leadscrew; iii) a first actuator module including a first actuator fortranslating the first lead screw threaded portion; and iv) first meansfor sensing configured to detect rotation of the first lead screw; c) asecond optics assembly, comprising: i) a second lead screw including athreaded portion, a first end, and a second end; ii) a second opticsgroup coupled to the first end of the second lead screw so that rotationof the second lead screw results in translation of the second opticsgroup along an axis of the second lead screw; iii) a second actuatormodule including a second actuator for translating the second leadscrew; and iv) second means for sensing configured to detect translationof the second optics group; and d) an image sensor.
 11. The auto-focusand zoom module of claim 10, wherein the first optics group is coupledto the first end of the first lead screw by a first spring configured tobias the first optics group against first end of the first lead screw.12. The auto-focus and zoom module of claim 10, wherein the secondoptics group is coupled to the first end of the second lead screw by asecond spring configured to bias the second optics group against firstend of the first lead screw.
 13. The auto-focus and zoom module of claim10, wherein at least one of the first actuator and the second actuatoris a cylindrical vibrational actuator.
 14. The auto-focus and zoommodule of claim 10, wherein at least one of the first actuator and thesecond actuator is constrained at a node point by a flexible coupling.15. The auto-focus and zoom module of claim 10, wherein the first opticsgroup and second optics group are configured to provide an image havinga focus and a magnification to the image sensor.
 16. The auto-focus andzoom module of claim 10, wherein the image sensor is selected from thegroup consisting of: complementary metal oxide semiconductor (CMOS) anda charge-coupled device (CCD).
 17. The auto-focus and zoom module ofclaim 10, wherein both the axis substantially parallel to that of thefirst lead screw and the axis substantially parallel to that of thesecond lead screw are parallel to a first guide pin.
 18. An auto-focusand zoom module, comprising: a) a first guide pin; b) a second guidepin; c) a first optics assembly, comprising: i) a first lead screwincluding a threaded portion, a first end, and a second end; ii) a firstoptics group coupled to the first guide pin and the second guide pin andincluding a drive target and a spring interface feature; iii) a firstspring coupled to the spring interface feature and configured to urgethe drive target of the first optics group against the first end of thefirst lead screw; iv) a first actuator module including a first actuatorfor translating the first lead screw; and v) first means for sensingconfigured to detect rotation of the first lead screw; d) a secondoptics assembly, comprising: i) a second lead screw including a threadedportion, a first end, and a second end ii) a second optics group coupledto the first guide pin and the second guide pin and including a drivetarget and a spring interface feature; iii) a second spring coupled tothe spring interface feature and configured to urge the drive target ofthe second optics group against the first end of the second lead screw;iv) a second actuator module including a second actuator for translatingthe second lead screw; and v) second means for sensing configured todetect translation of the second optics group; and e) an image sensor.19. The auto-focus and zoom module of claim 18, wherein the first opticsgroup and second optics group are configured to provide an image havinga focus and a magnification to the image sensor.
 20. The auto-focus andzoom module of claim 18, wherein the image sensor is selected from thegroup consisting of: complementary metal oxide semiconductor (CMOS) anda charge-coupled device (CCD).
 21. An auto focus and zoom module,comprising: a) a housing b) an optics assembly, comprising: i) a leadscrew including a threaded portion, a first end, and a second end; ii)an optics group coupled to the lead screw so that translation of thelead screw results in translation of the optics group along an axisparallel to the lead screw; iii) a vibrational actuator of the type thatoscillates in a standing wave pattern to drive a threaded shaft placedtherein to rotate, thus translating the threaded shaft, coupled to thethreaded portion of the lead screw and constrained at a node point ofits preferred standing wave pattern by a flexible coupling with thehousing; and iv) means for sensing configured to detect rotation of thelead screw; and c) an image sensor, wherein the optics group isconfigured to provide an image having a focus and a magnification to theimage sensor.
 22. An actuator module, comprising: a) a vibrationalactuator of the type that oscillates in a standing wave pattern to drivea threaded shaft placed therein to rotate, thus translating the threadedshaft, having a preferred standing wave pattern; b) a lead screwcomprising a threaded portion, a first end, and a second end, thethreaded portion coupled to the vibrational actuator; c) an actuatorhousing, with an actuator retention region therein; and d) a flexiblecoupling structure, coupled to the vibrational actuator at a node pointof the preferred standing wave pattern, and also coupled to the actuatorhousing.
 23. The actuator module of claim 22, wherein the actuatorretention region is a five-sided chamber, with an opening on one side,sized to fit a parallelepiped containing the vibrational actuator sothat a surface of the vibrational actuator is parallel with the opening.24. A method of implementing a hard stop on a body driven along an axisby threads disposed orthogonal to that axis, comprising: a) coupling afeature to the body to form an assembly having non-symmetric regionrelative to the axis; b) driving the body by the threads using anactuator; c) coupling a movable element to a point fixed relative to theactuator, wherein the movable element has a latch feature configured tomate with the non-symmetric region; and d) disposing the movable elementat a position such that the latch feature mates with the non-symmetricregion and prevents rotation of the body.
 25. The method of claim 24,wherein the step of disposing the movable element is performed in partby moving the movable element by driving the body against it.
 26. Themethod of claim 24, wherein the feature coupled to the body is a cam.